In your thirties, collagen and elastin are reduced and skin cell turnover is slowed, which often leads to dry or dull-looking skin. Sun exposure may produce brown patches called melasma on the cheeks, forehead, or chin. Pregnancy and birth control have also been known to trigger melasma. People in their thirties should include anti-aging products in their skincare routine. Exfoliate regularly to encourage skin-cell turnover.